Sberbank declined to comment. Yandex, which was not available to comment, was expected to hold a news conference on Wednesday.

Sberbank, which accounts for a third of overall lending in Russia, has been expanding in the consumer credit market amid weak corporate loan portfolio growth.

In recent years, it has launched its own credit card business and tied up with French bank BNP Paribas in a joint venture focusing on point-of-sale lending, a popular form of in-store consumer finance in Russia.

Yandex, which raised $1.4 billion when it floated on the U.S. stock market in May 2011, came under scrutiny during election protests over the past year when it was reported that opposition leaders were raising funds via Yandex.Dengi.